Polymer solar cells are a class of thin film solar cells where the film can be made without using much expensive and difficult vacuum techniques.. The films can be made by simple spin coating or doctor's blade technique. Efficiency achieved in polymer solar cells are quite low compared to other forms of thin film solar cells like amorphous- Silicon or dye-sensitized solar cells. The common polymers used are PCBM, P3HT etc., Here polymers act as both n-type and p-type layers with an optional absorber layer in between them.

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As @atabaev said, According to research and recent studies, the potential to increase the efficiency of thin films, over current solar cell compositions differs by 2-3 times of its efficiency. these approaches lead to a Quantum jump in thin film solar cell efficiency. and so In future these thin films remains highly speculative. Several papers have been discussed so far. In case of Ref: Thin-Film Solar Cells: Next Generation Photovoltaics and Its Applications
edited by Yoshihiro Hamakawa (Book)
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